Dr. Jarrod Hardke
June 24, 2016 No. 2016-15 www.uaex.edu/rice
Standing outside has felt like standing in front of either a hot blowdryer or a blowtorch depending on your perspective. Hot, humid conditions have the rice crop progressing well, but all those out in it perspiring well.
With the high humidity and heavy dew periods in the mornings we’ve had our first reports of blast and sheath blight this week. So far nothing to get worried about in any case, but we have found them scattered around.
Most are looking forward to the next week where there are rain chances (FINALLY!). We’ll see if the forecasts come through for us or if they fizzle out once again. Rains are seriously needed and many are starting to get behind. It looks like the old saying may hold true once again – “we better get a 4th of July rain, because if we don’t we’re in trouble.”
Speaking of July, between July 5-25 over 90% of our rice crop will hit 50% heading. With the way rice stink bugs are lurking in fields they’re ready for it. With the large acreage set to head out together hopefully we can spread them out and escape major damage.
Rain chances and possibly escaping some stink bug damage is the good news for the week. Everything else deals with production problems! On the upside the majority of acres still look great, we’re just cleaning messes and problem fields primarily. Without dwelling on it, injury from glufosinate drift has been common (Fig. 1).
Fig. 1. Glufosinate (Liberty) drift to rice – injury is typically cosmetic w/ no yield loss.
Shorter Rice with Rows Still Clear
A number of calls about older rice that normally would be well-canopied but the rows still stand out. The common denominator for this effect has been where some amount of dirt work was done this winter – even as simple as a finishing pan or a larger leveler. Normally we wouldn’t see these types of effects but apparently the dry winter we had followed by a wet early spring has limited some of our plant growth response and possibly nutrient availability due to shallow rooting.
We observed the first sign of this months ago when severe plant injury from a very safe herbicide rate. Injury and stand loss occurred where some light dirt work had been done – but it stopped halfway across the field. Of course the other half of the field looked beautiful.
Plant height alone is not an indicator of yield potential. As long as we have good plant color and a healthy number of tillers we’re still in the ballgame.
Reports of Problems with Hydrogen Sulfide Toxicity on the Rise
To echo what’s been said the past couple of years – we’re still not sure if hydrogen sulfide toxicity (Fig. 2) is on the rise or if we’re just doing a better job scouting and looking for it.
The point is – near midseason if odd field patterns or deficiency symptoms show up CHECK THE ROOTS! We should be pulling up plants and checking for joint movement anyway so a quick second to wash the roots and look them over is well worth it. Even in the weeks immediately following flood it’s best to occasionally check roots since this problem can begin any time after flooding.
Fig. 2. Hydrogen sulfide toxicity causing severe injury (right) compared to rice on the levee (left).
Blast & Sheath Blight Reported
Blast and sheath blight reports have emerged in the past week. Blast has been reported in Woodruff, Lawrence, and Prairie Counties (Fig. 3). No need for alarm, occasional lesions are all we’ve found.
Asked earlier about the likelihood of disease picking up – conditions didn’t seem that favorable given the high temperatures. However, the long dew periods and high humidity we’ve been having are apparently enough to start some disease progression.
The forecast for the coming week is the biggest concern – with cooler and wetter conditions disease may take off. We can hope not but the reverse would be no rain and irrigation running non-stop. One way or another we’ll get something we don’t want.
Fig. 3. Blast lesions starting to show up.
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